Method and apparatus for minimum negative pressure control, particularly for a breastpump with breastshield pressure control system

ABSTRACT

A breastpump, manual or motorized, that includes a mechanism to regulate pressure change, e.g., vacuum, within a breastshield chamber, including in some cases to a maintained minimum pressure that is less than ambient (atmosphere). The pressure regulator provides control for varying negative pressure between a minimum value and a maximum value (and values in between), or to achieve a specific actually measured negative pressure value within a breastshield.

FIELD OF THE INVENTION

This application is a continuation-in-part of application Ser. No.11/786,364 filed on Apr. 11, 2007 entitled “Method and Apparatus forMinimum Negative Pressure Control, Particularly for Breastpump withBreastshield Pressure Control System.”

This invention relates to breastpumps for drawing breastmilk, andparticularly to a breastpump whether operated manually or motorized,with a pressure control system to regulate the pressure as actuallyapplied to the breast within a breastshield chamber during a pumpingcycle, and also to vary that pressure in a cycle that maintains aminimum vacuum.

BACKGROUND OF THE INVENTION

Breastpumps for use by nursing mothers are well known. They allow thenursing woman to express the breastmilk as necessary or convenient, andfurther provide collection of the breastmilk for later use. For somemothers, breastpumps may be a necessity, such as when the child hassuckling problems, or if the mother has problems with excessive ordeficient milk production, or soreness, deformation or injury of themammilla, or like conditions that are not conducive to suckling at thebreast.

There are three general broad classifications of breastpumps: hand pumpsthat generate suction manually, battery operated pumps with small motorsthat generate suction from power supplied by batteries, and electricpumps in which suction is created by various types of electric motorsthat run off “house” current. Some pumps can cross over these broadclassifications.

Various types of hand pumps exist. An example of such manually-drivenpumps is in U.S. Pat. No. 6,497,677.

A battery-driven portable breastpump is described in U.S. Pat. No.4,964,851, for example. This breastpump is small, lightweight andachieves good vacuum (i.e., negative pressure) regulation in preferredlimits. The LACTINA breastpump sold by Medela, Inc. is also another typeof breastpump, which may be driven by battery as well as house current.It is generally disclosed in U.S. Pat. No. 5,007,899.

All of these breastpumps are designed to cycle pressure, typically anegative pressure or vacuum, that is applied to the breast and nipplewithin the breastshield. Conventional breastpumps are generally of thedisplacement pump type or accumulator pump type. Displacement pumps usea mechanism to expand a volume to thereby generate a vacuum, such as theforegoing piston-type pumps. At the end of the return stroke, theyreturn to atmosphere. A maximum (or other) vacuum is achieved by thelength of the stroke. Upon returning the breast shield to atmosphericpressure, a one way valve may be opened to discharge accumulated leakageair, excess air from the repositioning of the breast tissue, andexpelled milk within the breast shield. The discharge occurs into anatmosphere vented milk collection bottle or flexible bag. Alternatively,air can be adjustably added during a fixed-length stroke (as by anadjustable return to atmosphere) to roughly establish a desired vacuumlevel.

Accumulator pumps build up vacuum by repeatedly exhausting smallportions of the original quantity of gas in the system. As the amount ofgas (air) in a fixed volume decreases, the pressure decreases causingthe vacuum to increase. Accumulator pumps control the maximum vacuum viathe time, or duration, the pump is powered on and operating, e.g., thenumber of pump reciprocations for a given cycle. Vacuum can also beadjusted via a regulator, like that of the battery-driven portablebreastpump described in U.S. Pat. No. 4,964,851, for example.

An issue with conventional breastpumps is that the “system” volumewithin the breastshield varies due to the amount of volume the breast ofa nursing mother occupies in the breastshield, as well as the responseof a given breast under vacuum. For example, a nursing mother withengorged breasts will have tight breast and nipple tissue that mayoccupy the breastshield differently from a mother with highly elasticbreast tissue and/or nipples. So too, a small breast or nipple may fillthe breastshield and react differently from a large breast or nipple.The system volume thus varies from breast to breast, and even from timeto time for the same breast.

This “variable system volume,” sometimes referred to as the “dead”volume, is problematic within a suction cycle. Imagine a highly elasticbreast/nipple; at the start of the suction cycle, the breast and nippleoccupy a certain portion of the breastshield system volume. This fixesthe starting quantity of air in the system. As suction builds, thebreast/nipple tissue is drawn into the breastshield, partially relievingthe buildup of vacuum. Thus, the developed vacuum within the cycle isless than would be realized with a less elastic breast/nipple.

To the extent that conventional breastpumps of the displacement oraccumulator types have attempted to provide actual set points for vacuumdesired, they do so only through an approximation. A vacuum setting of“250 mmHg” for such pumps would only be for a standard sized breast forexample, since it is based upon an expected level derived fromdisplacement, or alternatively accumulation, effected by operation. Themethod or mechanism by which a vacuum is regulated is thus notcontrolled by the actual pressure sensed at the breast.

Some prior art patents disclose regulating pressure with a sensedpressure. U.S. Pat. No. 5,902,267 to Medo discloses a regulator within acentral vacuum system that applies the regulated output to a pump“flange” on the breast, and then returns to ambient pressure in a cycle.

U.S. Pat. No. 6,383,163 to Kelly discloses a vacuum sensor for sensingsuction in the breast cup and opening a valve when a maximum suction issensed to release the pressure and return the breast cup to ambient.Upon the breast cup achieving ambient pressure, the valve closes foranother cycle.

Unlike the present invention, the prior art does not regulate vacuum atthe breastshield to reach a maximum negative pressure, and then adesired minimum negative pressure still less than ambient, without theneed to return to atmospheric pressure for successful milk expression. Areturn to ambient pressure within the breastshield chamber may not berequired, and benefits may be achieved by maintaining a minimum level ofvacuum on the breast throughout at least a portion of the pumpingsession. Such would include, for example, reducing the amount of energyrequired to thereafter reach maximum vacuum. The “elastic rebound” ofthe nipple upon release of vacuum would also be minimized. Furtherbenefits may result from being able to control a given vacuum cyclebetween desired set points of actually sensed, and thereby actuallyapplied pressures, which set points may be made numerous for morecomplex, yet precisely controlled suction curves. The present inventionalso provides comfort to the nursing mother in that the reciprocation ofa breast or nipple within the breastshield is minimized.

Patent application Ser. No. 11/786,364 entitled “Method and Apparatusfor Minimum Negative Pressure Control, Particularly for Breastpump withBreastshield Pressure Control System,” describes means of using anaccumulator breast pump with sensors to control the vacuum cycleprecisely including the minimum vacuum. The application describes abreast shield which, when in contact with a breast, has internalpressure controlled by the control system, and where the internal breastshield pressure communicates with the milk collection bottle to bringthe bottle to the minimum vacuum. Some slight cyclic variation togreater vacuum occurs each pumping cycle within the bottle collection.The collection bottle is sealed from the atmosphere. Opening of the oneway valve is assisted by the higher vacuum in the bottle as the breastshield approaches the minimum vacuum, a lower vacuum.

SUMMARY OF THE INVENTION

It is a principal objective of the present invention to provide abreastpump, either manual or motorized, that includes a mechanism thatcan be used to regulate pressure change, e.g., vacuum, within abreastshield chamber, and even fairly precisely regulate that pressurein one preferred form.

The present invention in another significant aspect operates a pumpingcycle that maintains a minimum level of vacuum within a breastshieldchamber throughout at least some, if not all, of a pumping session. Adesired minimum level can be attained such that a nipple does notachieve a relaxed state. A minimum vacuum in the range of about 20 mmHgto about 60 mmHg is presently considered most desirable, although about15 mmHg is also considered desirable.

In an embodiment, a regulator used in conjunction with a motorized pumpthat regulates vacuum within a breastshield chamber operates accordingto a controller and actual sensed vacuum to the breast, with presetinstructions or user input parameters, and may automatically transitionbetween different operating conditions according to the presetinstructions (e.g., a letdown sequence followed by an expressionsequence), or operate according to a user input, or both.

Another significant advantage realized by the present invention is theability to precisely regulate pressure changes within the breastshieldchamber, so as to control pressure during a pumping cycle through aplurality of desired set points, including in some cases to less thanambient (atmosphere) during part of a cycle and then back to a maximumnegative pressure.

An object of the present invention is to control minimum and maximumvacuum levels at the breastshield to alleviate issues associated withsystem volume, i.e., the volume of air in the system. Another andrelated object of the present invention is to enhance development ofadvanced systems, i.e., miniaturization of a breastpump system, itsphysical size, and power requirements, by decreasing the amount of workper suction cycle and therefore energy expended; the less work, thelonger the battery life for a battery operated pump. Also, a potentiallysmaller motor can be used at reduced motor speed (for less noise).

Maintaining a minimum (or partial) vacuum also serves to minimizeelastic rebound of the nipple seen in conventional systems that returnback to atmospheric pressure. As the breast or nipple pulls into orretracts back within the breastshield, the system volume changes. Thepresent invention allows for a more stable volume upon which the pumpmust act. A more stable volume also alleviates discomfort and irritationby minimizing the reciprocations of the breast or nipple within thebreastshield. Milk may also continue to be removed during the baselinevacuum.

Additionally, the duration vacuum is applied to the breast to activelyremove milk can be precisely controlled. An intelligent system, or“smart pump”, can replicate a desired curve (suction pattern, orsequence) during each cycle.

Another object of the present invention is to maintain a minimum vacuumto hold or assist the hold of the breastshield onto the breast bysuction for a “hands free” use, or partially hands free feature in someinstances.

Another object of the present invention includes a valve that opens in amilk catch chamber due to differential pressure across the valve, wherethat pressure differential assists in opening the valve. The valve opensto allow the milk accumulated above the valve to empty into thecollection container. In one form of the present invention, milk isactually drawn (forced) through the valve and into the container by avacuum present in the container. This allows the use of more robustvalves to pass milk through the valve using the vacuum in the collectioncontainer. The differential pressure allows for the utilization of checkvalves, e.g., a “duckbill” valve, with higher opening forces as well asa wider range of opening forces to maintain reliable operation andlonger life.

In yet another aspect of the invention, a regulated pressure within abreastshield chamber of a breastpump allows for consistency between:pump cycle to pump cycle; mother to mother; and pump session to pumpsession, such as may be due to variable (breast to breast), or changing(nipple moving into and out of the breastshield during the pumpingcycle) system volume within the breastshield.

With a pressure sensor, a very precise pressure curve can not only beachieved, but tailored as desired, and then reproduced at a laterpumping session.

In yet another embodiment, the breast pump includes a pressure controlsystem having a valving arrangement that is located at the vacuum pump,rather than at or on the breastshield assembly. In one form of thisembodiment, three one way valves are used. Two are an umbrella andduckbill combination; the third is a flap or reed valve that is used topurge excess air from the system. All valves are statically closed andare opened by pressure across the valve, i.e., they are operatedpneumatically.

Outside of the breastpump environment, embodiments of the presentinvention have potential application to what is referred to as negativepressure wound therapy. The latter is generally described in the BlueSkyMedical Group, Inc. Chariker-Jeter or Wooding-Scott drainage kits, andChariker, M. et al., Effective Management of Incisional and CutaneousFistulae with Closed Suction Wound Drainage,” Contemporary Surgery, vol.34, pp. 59-63 (June 1989). A reduced pressure, which may beintermittently applied, has been shown to have therapeutic benefit uponwound treatment and healing.

These and other features and advantages of the present invention will befurther understood and appreciated when considered in relation to thefollowing detailed description of embodiments of the invention, taken inconjunction with the drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an embodiment of a manual breastpumpaccording to certain aspects of the present invention;

FIG. 2 is a side view of the breastpump of FIG. 1;

FIG. 3 is an exploded sectional view of the majority of the breastpumpassembly of FIG. 1;

FIG. 4 is an enlarged view of the parts of one valve mechanism of thebreastpump of FIG. 1;

FIG. 5 is an exploded side sectional view of the valve mechanism of FIG.3 and regulator;

FIG. 6 is a side elevational view, partly broken-away and alsoschematic, of another embodiment in a motor driven breastpump accordingto certain aspects of the present invention;

FIG. 7 is a schematic view of another arrangement for controllingpressure in a breastpump of the type of FIG. 6;

FIG. 8 is a diagrammatic representation of various components of acomputer operated breastpump according to another embodiment of thepresent invention;

FIGS. 9 through 12 are various representative methods (curves) foroperating a breastpump between differing maximum and minimum vacuumlevels by regulating pressure;

FIG. 13 is an enlarged view of the parts of an alternate embodiment of avalve mechanism of the type that could be adapted for the breastpump ofFIG. 1;

FIG. 14 is a side view of an alternate embodiment of another regulator;

FIG. 15 is a perspective view of a “hands-free” type embodiment of abreastshield according to an aspect of the invention;

FIG. 16 is a perspective view of another embodiment of the inventionusing two duckbill valves;

FIG. 17 is a downstream end view of the embodiment of FIG. 16;

FIG. 18 is still another embodiment, similar in view to that of FIG. 6;

FIG. 19 is yet another variation on the inventive theme. This version isadapted to function with a vacuum source 216 which draws the vacuum tothe desired minimum, but without necessarily venting portions of thesystem to ambient (as done in some of the other embodiments).

FIG. 20 is another embodiment of a pressure regulator;

FIG. 21 is a cross section of the breast shield and collection bottleinterface for a non-barrier system;

FIG. 22 is a variation of FIG. 21 for a barrier system;

FIG. 23 is a sectional view of a breastshield similar to that of FIG. 2,for another embodiment of the present invention having a modified valvemechanism like that of FIG. 13;

FIG. 24 is a base mounting member for use with the embodiment of FIG.23;

FIG. 25 is an enlarged elevational sectional view of the base mountingmember of FIG. 24;

FIG. 26 is a top perspective view of a valve membrane for mounting onthe base mounting member of FIG. 24; and

FIG. 27 is a bottom perspective view of the valve membrane of FIG. 26.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

One embodiment of the invention is shown in a manual breastpump of FIGS.1 through 3, here of the type as detailed in U.S. Publication No.2004/0039330, incorporated herein by reference. This type of breastpumpis simply illustrative, and not intended to be limiting of theinvention.

The breastpump assembly 110 includes a shield 112, for contacting thebreast. The shield 112 is attached to a conduit structure 114. A vacuumpump mechanism 116, in this instance a handle (lever) 117 which ishand-driven, is attached to the conduit structure 114. The conduitstructure 114 transmits vacuum generated in the vacuum pump mechanism116 to the shield 112, and transmits expressed breastmilk from theshield 112 to an attached container 118.

The shield 112 has a generally funnel portion 120 shaped and sized forbeing received onto a breast. The shield 112 extends into a sleeve 122downstream from the funnel shaped portion 120. The sleeve, or nippletunnel, 122 conducts expressed milk into the conduit structure 114. Forpurposes of the instant invention, the shape of the shield 112 and itsformation with the conduit structure 114 are generally incidental to theinvention; again, the particular arrangement and details of theseelements is in no way limiting.

The conduit structure 114 is attachable to the shield 112 through ashield mount 124 sized and shaped to receive the sleeve 122. The conduitstructure 114 is generally a housing (base) that interconnects andpermits fluid communication between parts of the breastpump assembly 110that includes not only milk flow, but also pressure (e.g., vacuum)communication. Here, the conduit structure 114 connects to the sleeve122, by way of the shield mount 124 at an upstream end, and terminateswith a valve mechanism (not shown in FIG. 3) as is known in the art (seethe aforementioned patent publication disclosure) at a containerattachment end 126. The container attachment end 126 may include threads128 (FIG. 3) or any suitable mechanism for releasable attachment tocontainer 118, which may be in the form of a milk bottle or the like. InFIG. 3, the conduit structure 114 includes a channel 130 for conductingexpressed breast milk from the shield mount 124 and into the container118. The conduit structure 114 also includes a receptacle or well 134for receiving the pump mechanism 116 and conducting the air pressurechange (here, a vacuum) effected by movement of the pump handle 117,with its related expansible chamber device (again, see theaforementioned patent publication disclosure).

A pressure regulator 160 (shown highly schematically, but of a type wellknown in the art) has the ability to regulate the pressure within thebreastshield 112 so as to control pressure during a pumping cycle. Avery easy manually operated regulator 160 is provided that operates soas to set a specific vacuum level to maintain a minimum level within thebreastshield during expression of breast milk. The regulator 160 in thisinstance is manually operated, and of the general type disclosed in U.S.Pat. No. 4,964,851. Besides manually adjustable regulation, regulationcan be automated, as discussed more fully below with respect toalternate embodiments, or the regulator mechanism can further madeunadjustable in certain embodiments, also as discussed below.

As shown in FIG. 3, the regulator 160 works in conjunction with a valvemechanism to allow for the milk drawn from the breast to travel to thecollection container 118, while maintaining a minimum vacuum in thebreastshield. More particularly in reference to FIGS. 4 and 5, the valvemechanism generally consists of a rigid wall or base 172 and a thinflexible membrane 174 (or flap), made of rubber or silicone rubber; suchis detailed in U.S. Pat. No. 4,929,229, incorporated herein byreference. The wall 172 is circular (disk-like) in shape, and can eitherbe removably engaged or integrated with the shield mount 124. Wall 172includes four openings 180, 182, 184, 186. Opening 184 is located at apoint that is roughly at the center of the wall 172. Openings 180 and182 are formed through the wall 172 along the bottom of the wall 172.

Opening 186 is for engagement with the membrane 174. The thin flexiblemembrane 174 has a generally circular (disk-like) shape and is attachedto the wall 172 by way of knob (nub) 176, which is engaged in opening186 in a snap fit. The diameter of the membrane 174 is sufficient enoughto completely cover the wall 172 and openings 180, 182, 184. The valvemechanism 172, 174 is positioned within the shield mount 124 upstream ofthe channel 130.

Referring to FIG. 3 and FIG. 5, the regulator 160 includes a manualadjustment mechanism 162 located in a pressure channel structure 164.The regulator 160 is positioned within the shield mount 124 such thatthe adjustment mechanism 162 is accessible to be manually adjusted fromthe outside of the breastpump system. The pressure channel structure 164extends outside the shield mount 124 to communicate at a second end withthe channel 130. That is, the second end of the pressure channel 164communicates with a gap 132 leading to the channel 130. Of course, thechannel 164 could be made internal with the sidewall structure of theshield mount, or otherwise establish an air channel between the upstreamand downstream sides of the valve 172, 174.

The pressure regulator 160 provides simple manual control for achievingand varying the negative pressure. The nursing mother can now maintain adesired minimum negative vacuum level, as follows.

The regulator 160 is adjusted to the level desired. As the cycle goes to(or at least toward) ambient pressure, the valve flap 174 engages thewall 172, closing off the breastshield from the rest of the breastpump.The negative pressure within the breastshield 112 continues to drop,however, as the system cycles back toward ambient from maximum negativepressure and higher pressure air passes through the pressure channel164.

Vacuum in the breastshield 112 is maintained at the adjusted minimumwhile the nursing mother moves the pump handle 117 through the strokeuntil atmospheric pressure or even a slight positive pressure exists inthe channel 130. A valve (not shown, but standard) between bottle 118and milk retention chamber 168 that communicates with channel 130 opensto express the milk into the bottle.

With reference to FIG. 5, when the negative pressure reaches the presetminimum, regulator 160 closes, or shuts off air flow, maintaining thedesired negative pressure within the shield 112. When the downstreamvacuum level thereafter exceeds the preset minimum (e.g., desired,selected, or otherwise defined) on the next cycle, the valve 172, 174opens.

It may be noted that the minimum vacuum maintained in the breastshieldcould be released through a relief element, for example, a relief valvepositioned on the breastshield itself. The mother can also simplymanipulate a portion of the breast to break the vacuum, or just pull thebreastshield off her breast.

An alternate embodiment of the thin flexible membrane 274 is shown inFIG. 13. This embodiment includes a slit 277 along with nub 276 for asnap fit engagement (the latter on the base 172). The slit 277 islocated substantially in the center of the membrane 274, but anyposition of the slit is contemplated such that it opens and closes at adesired pressure. In this FIG. 13 embodiment, the slit is sized inconjunction with the natural resilience (elasticity) of the membrane, sothat it closes at the desired minimum vacuum (say, negative 50 mmHg).There is no ability for the user to adjust the minimum vacuum (sincethere is no adjustable regulator used in this version), but a verysimple mechanism for maintaining a desired pressure is provided. It isnonetheless tailorable (via slit manufacture) at the factory, forexample, to an approximate desired minimum vacuum, and is reasonablydurable. There are other ways to do this slit-like concept, such as oneor more pinholes, for example, which would remain open until thepressure reached the point where the natural resilience of the materialdefining the hole(s) causes closure.

Yet another alternative for the thin flexible membrane 274 is shown inthe embodiment of FIGS. 23 through 27. As shown in FIG. 27, thisflexible membrane 850 has two slits 277, which are shown generallyparallel and slightly spaced apart. These slits 277 are formed throughan enlarged nub 852. Nub 852 has a planar part 854 (within which theslits 277 are formed), and a somewhat radially widened circumferentialbulge or annulus 856 between the planar part 854 and the major planarringlike part 858 of the membrane. Reinforcing bumps 860 are formed onthe downstream end of the ringlike part 858 (downstream relative to milkflow, as will hereafter be evident in discussion of the mounting of themembrane 850). These reinforcing bumps 860 serve to stiffen the membraneagainst being drawn into apertures (or otherwise deformed) in the baseor mounting member to which it is attached, and with which it functionsto form a valve.

That mounting member 862 is shown in FIGS. 24 and 25. Mounting member862 is a short cylindrical piece having a sidewall 864 and a planarringlike base 866. The ringlike base 866 extends radially outwardly onone side surface into a shoulder 868, which circumscribes this side ofthe mounting member. Holes 870 are formed through the base 866 aroundits surface, through which fluid (milk or air) may flow; while circularholes are shown, other shapes (e.g., kidney) could be used for thethroughholes. A nub-receiving aperture 872 is formed generally centeredon the base 866. The nub 852 is received in this aperture 872, with thebulge 856 passing therethrough from one side to the other, with the nowdownstream side of the bulge 856 then serving to fix the membrane inplace by engaging with the upstream side of the mounting member 862. Theringlike part 858 of the membrane is sized to cover the holes 870, andgenerally extend to about the shoulder 868.

The mounting member is adapted to fit over the downstream end of thenipple tunnel 878 of the breast shield 876, which has a funnel part 880.To that end, the mounting member 862 has an angulated upstream end tofit over the outside of the nipple tunnel in an interference fit (or itcould be made to flex inwardly to mount within the nipple tunnel in asimilar manner).

This double-slit 277 version is considered to give better minimum vacuumcontrol over a broad range of maximum vacuum.

Another embodiment of a simple but robust pressure regulator is shown inFIG. 14. As shown in FIG. 14, the regulator 500 includes a rigid pin 502having disks 503 and 504 at each end thereof. The regulator 500 can movealong the longitudinal axis of the pin 502 within a dome 506. Dome 506is fixed in, or as shown here made integral with, a flexible membrane508, such as that described vis. flap 174. Dome 506 is thus flexible,and essentially forms a spring-like element. That is, dome 506 is sizedwith the pin 502 so that the dome 506 presses the disk 503 away from themembrane 508 while simultaneously pulling the disk 504 in sealingengagement with a seal ring 505. The amount of force exerted by the dome506 on the pin 502 is tailored to the minimum vacuum desired. An opening507 is formed through the dome to allow air to pass from one side of themembrane to the other. Alternatively, the hole 509 through which the pinpasses can be adapted to yield this air pass in operation. As noted, theregulator 500 is adjusted to shut at the minimum vacuum; when thenegative pressure within the rest of the breastpump drops towardambient, the flap 508 closes against the base as previously discussed.The vacuum within the breastshield then causes the disk 504 to unseat,allowing the higher pressure air to be pulled into the breastshieldthrough the hole 507. The minimum pressure is reached within thebreastshield when the pressure differential is no longer enough toovercome the spring force exerted on the disk 503 by the resilient dome506, and disk 504 seats. Yet other forms of a simple yet robustregulator that could be adapted for use with the invention would be anumbrella valve, a duckbill valve or a combined umbrella/duckbillcheck-relief valve, such as that described in U.S. Pat. No. 3,159,176.

FIGS. 16 and 17 show yet another variant which uses two duckbill valvesto establish and maintain the minimum desired vacuum. This type ofbreastshield is a monolithic version made of a flexible silicone, suchas disclosed in U.S. Patent Publication 2005/0222536, filed Mar. 31,2005. The nature of the breastshield is of course merely incidental tothe invention, as previously noted. Breastshield 360 has an opening 362to receive the nipple and some surrounding breast. Downstream from theopening 362 is a first duckbill valve 364 which seals this downstreamend 366 of the breastshield. The first duckbill valve 364 is of aconventional construction, also being made of a flexible material, witha downstream opening for this valve at 368.

A second duckbill valve 370 is located in a conduit or throughbore 372formed through the upstream flange 374 of the first duckbill valve 364.It is generally the same type as the first duckbill valve 364, but muchsmaller. The downstream end of the throughbore 372 terminates in anopening 378 which communicates with the vacuum being generated for thebreastshield in general. The upstream end of the throughbore 372communicates with the interior of smaller duckbill valve 370. Smallerduckbill valve 370 is designed to close at the minimum pressure (vacuum)desired to be maintained inside the breastshield throughout a pumpingcycle.

This is how the foregoing double-duckbill embodiment works. When thepumping sequence goes toward ambient within the system, first duckbillvalve 364 closes (higher pressure now being present downstream thanwithin the breast shield interior). The pressure differentialnonetheless causes air to pass through smaller duckbill 370, however, tothe interior of the breastshield, until the natural (and preselected)resilience of the smaller duckbill valve 370 causes it to close, at theminimum desired vacuum to be maintained.

Of course, the invention is readily adaptable for a motorizedbreastpump. The breastpump may be manually adjustable to produce simplevacuum and cycle frequency conditions within the breastshield, or may beuser programmable as detailed in U.S. Pat. No. 6,547,756 for morecomplex pumping cycles or curves, or may have both capabilities.

As previously noted, the invention has application beyond a breastpumpenvironment. For example, the embodiment of FIGS. 16 and 17 could beadapted for negative wound therapy. The opening 362 would be widened,for instance, and the axially extending portion 380 made much shorter.The rest of the system would need little or no modification to adapt tothis other therapeutic application.

As shown in FIG. 6, this breastpump assembly 210 includes a shield 212,shaped and sized for being received onto a breast. The shield 212 isattached to a conduit structure 214. A vacuum pump mechanism 216 isattached to the assembly 210 via an airline 218. The pump 216 iscontrolled by a controller 220. The airline 218 transmits vacuumgenerated in the vacuum pump 216 to the shield 212. The airline 218includes an adjustable pressure regulator 260 that regulates the vacuumlevel within the breastshield 212 when valve 280 is open.

The conduit structure 214 conducts expressed breast milk from thebreastshield 212 through a duckbill valve mechanism 270 and into themilk container 228. A vent 275, as further described below, is used inconjunction with the valve 270.

A solenoid valve 280, which is operated by the controller 220, is inseries with the regulator 260, in ambient airline 290.

The manually adjustable regulator 260 has the ability to regulate theminimum negative pressure within the breastshield 212 (in the mannerpreviously described with reference to regulator 160). In this instance,it is located in the vacuum line 218 and the line to ambient pressure290.

As noted, solenoid valve 280 is operated by the controller 220, whichcontrols the pumping cycle. Controller 220 can be of many types, from asimple mechanical device that functions to operate the solenoid valve ata preset time or pressure in a cycle, to a microprocessor programmed todo the same. With the solenoid valve 280 closed (and the pump running),the vacuum increases in the breastshield 212 to a desired maximumwhereupon the solenoid valve 280 is opened, so the vacuum decreases inthe breastshield 212 toward ambient. When the negative pressure withinthe line 218 reaches the preset minimum of regulator 260, the regulatorcloses, and line 290 is closed off from line 218. This maintains aminimum negative (vacuum) level in the breastshield 212. The solenoidvalve is then closed to start the next cycle.

In use of the motorized breastpump, the assembly 210 system is initiallyat atmospheric pressure (or about 0 mmHg negative), the solenoid valve280 and duckbill valve 270 are closed upon the initiation of vacuumbuild-up. The regulator 260 is set to a predetermined value (e.g., 50mmHg negative). The vacuum in the breastshield 212 increases to amaximum value, as for example a value used for milk expression, usuallyaround 250 mmHg vacuum. Once the maximum value is achieved, the pump 216stops drawing a vacuum and the solenoid valve 280 opens such that theassembly 210 returns toward atmospheric, which causes the vacuum in thebreastshield 212 to decrease. When the preset minimum vacuum is reached,however, the regulator 260 shuts the line 290, holding the system at theminimum vacuum.

Expressed milk is collected within the catch chamber 221 above valve270. It will be noted that vacuum is also being generated in thecontainer 228. This is where the vent 275 comes into play in a uniquemanner. The vacuum in the container 228 increases as the air flows fromthe container 228 into the breastshield conduit structure 214 via thevent 275. This somewhat incremental increase in negative pressure withinthe bottle 228 ultimately is used to cause the valve 270 to open anddrop milk into the container 228. Subsequent cycles thereafterexperience this differential pressure across the valve 270 such thatmilk then drops through valve 270 into the container 228 during eachcycle thereafter due to the vacuum in the container 228 being greaterthan the vacuum in the breastshield 212.

More particularly, FIG. 11 represents such a method for operating abreastpump between differing maximum and minimum vacuum levels byregulating and tailoring pressures within the breastshield conduitstructure and the corresponding pressure within a collection container.The amount of pressure illustrated is shown at 0 mmHg negative (i.e.,ambient), with cycles maintained between a minimum pressure of about −50mmHg and maximum pressure of about −240 mmHg. Curve 700 represents thepressure within a breastshield while curve 600 represents thecorresponding pressure within a bottle. In reference to an automatedpump such as that of FIG. 6, the system is at atmosphere when thebreastpump begins operation. The solenoid valve 280 and duckbill valve270 (upon initiation of vacuum) are closed. The regulator 260 is set toa minimum pressure, −50 mmHg in this example. As the vacuum in thebreastshield 212 increases, represented by segment 702 in FIG. 11, thevacuum in the bottle 228 increases toward the minimum pressure (segment602). Although not shown on FIG. 11, it may take several cycles beforethe vacuum in the breastshield reaches the maximum level because of theinitial removal of air from the bottle. Once a maximum vacuum isreached, e.g., −240 mmHg, the solenoid valve 280 opens, and thebreastshield (and communicating internal structure) then returns back tothe minimum pressure. As the system returns back to the minimum pressure(which is still less than atmospheric pressure), the vacuum in thebreastshield 212 decreases (graph segment 704) while the vacuum in thebottle 228 continues to increase. At the end of the pumping cycle, theminimum pressure is reached in the breastshield 212 causing theregulator 260 to close the line 290. The vacuum in the breastshield 212maintains the minimum pressure for a duration of time (graph segment706), while the vacuum in the bottle 228 increases (becomes morenegative) slowly due to flow through vent 275. The above describedpumping cycle repeats a number of times, eventually creating a negativepressure in the bottle 228 (graph segment 608, and more particularly610) from additive vacuum, that forces the duckbill valve 270 open, somilk from the breastshield 212 flows into the collection container 228.What this therefore enables is the use of far more robust valves betweenthe conduit structure and milk container. The pressure differentialcreated between the bottle and milk catch chamber 221 is utilized toessentially propel the milk through the valve.

More particularly, FIG. 19 has a conventional shield 612 and nippletunnel 622. A catch chamber 621 is downstream therefrom, and has avalving mechanism 632 very much like that described in U.S. Pat. No.4,929,229 (general details of which can be gleaned from that patent).The membrane used herewith, however, is membrane 274 described above(and illustrated in FIG. 13 herein) as used in conjunction with the base172 (described, for instance, with respect to FIG. 4).

This FIG. 19 embodiment can be used with both a manual pump or amotorized pump 216. Here, it is depicted for use with a motorized pump.An adapter 634 is shown, which has a nipple 636 that connects with anairline 218 from the vacuum source 216. That nipple 636 extends to aninternal tube 638, which fits within a conduit 646 as hereinafterdescribed.

Adapter 634 mates with a collar part 640 of the breastpump via externalthreads 642 on adapter 634 that are match-threaded with internal threads644 to the collar 640. Collar 640 has an opening extending into conduit646, which communicates with the breastshield 612.

It will be noted that this, as well as other embodiments of theinvention, may further employ various means to separate the vacuumsource from the breastshield, for hygienic reasons as well as to protectthe vacuum source from moisture. Various such media separatingtechniques have been developed, as by Applicants' assignee Medela, andcan be found in U.S. Pat. No. 6,676,631 (see, e.g., FIG. 20 thereof),U.S. Pat. No. 5,941,847 and U.S. Ser. No. 11/591,276 (filed Nov. 1,2006), just to name a few.

Returning now to FIG. 19, this embodiment uses a vacuum sequence thatdoes not return to ambient, but instead takes the vacuum down from amaximum (e.g., about −250 mmHg), to the desired minimum (e.g., about −50mmHg), until once more returning to the maximum. This is essentially a“closed” system. Milk that is expressed collects in the catch chamber621 until the retained vacuum in the bottle 628 exceeds the minimumvacuum in the rest of the system. Using the membrane with slit (274,277), vacuum developed in the bottle at the maximum end of the cycledoes not completely return to the minimum (through selection of anappropriate cycle rate and slit 277 size). After a number of initialcycles, the vacuum building in the bottle permits the membrane 274 tounseat, and milk in the collection chamber to pass therethrough.

Where a manually operated regulator is shown in FIG. 6, an automatedpressure regulated system is shown in FIG. 7. A vacuum pump mechanism416 includes a vacuum line 418 and a solenoid valve 480 in an ambientairline 490. The pump 416 is controlled by a microprocessor basedcontroller 420, which further controls the solenoid valve 480 and isconnected with a pressure transducer 460.

The range (maximum, minimum and anywhere in between) of pressure valuescan be pre-programmed, or programmed by the user. With reference to FIG.8, for example, the breastpump utilizes a microprocessor-based systemindicated at 300, which is provided user input through a plurality of“chip” cards 301. Each chip card contains one or more predeterminedprograms that either varies pressure levels or maintains a specifiedpressure level within a breastshield, recorded on an EEPROM. Forexample, each card could contain a specific type of vacuum curve, orcombination of curves, to be realized within the breastshield. Moredetail of this kind of programmed sequence generation can be found inU.S. Pat. No. 6,547,756. As also described therein, many other inputmechanisms can be used to set or adjust the pumping curve(s). Otherinput means could be used, such as more dedicated buttons like button307 for a “letdown” sequence, and button 310 for a pre-set baselinevacuum in the breastshield, each set to actuate a given pressure levelor range into the microprocessor 300, and in turn to the breastshield. Anumeric pad could be provided to input a code for a particular programcycle, as well as desired vacuum level set points.

The particular program selected is then communicated to themicroprocessor 300. Microprocessor 300 is integrated with the drive unit303 to effect operation of the pump and to control the pressure inaccordance with the selected program, drawing upon a common power source(308 or 305).

Various maximum, minimum and pressure points in between can thus be setby the user or preprogrammed. Returning to FIG. 7, the pressuretransducer 460 then can relatively precisely determine the pressurebeing effected, sending a signal back to the controller 420 to governoperation. In this embodiment, the solenoid valve 480 is operated toadjust the vacuum between pressure points, by variably opening andclosing the valve in a controlled sequence. To operate the breastpump soas to maintain a desired minimum pressure, such as 50 mmHg vacuum in acycle, the valve would be opened at the set maximum negative pressure,opening the system to ambient (the rate at which it is opened likewisegiving some control over the curve being generated). At the point thatthe pressure transducer 460 detects (or anticipates achieving) thedesired minimum, the valve is closed, cutting off ambient air andholding vacuum in the breastshield. The microprocessor may thus beprovided with the capability to automatically transition the pressurewithin the breastshield from a maximum pressure to a minimum pressure(or ambient), and optionally to a pressure(s) in between.

It will be noted that there are electromechanical valves known in theart that could also be substituted and adapted for use in place of valve270, for instance.

Returning to FIG. 11, for example, this foregoing system could be usedto initially adjust the minimum pressure of the initial cycles toactually match that of the pressure build-up in the bottle, so that milkis dumped from the outset, rather than after several cycles. Graph point706 would thus be moved downward (as shown in FIG. 11) to that of graphpoint 606 (through use of an initially lesser pressure (i.e., vacuum)than the −50 mmHg depicted), with subsequent “minimums” being likewiseadjusted to increase until the desired −50 mmHg is reached.

Looking at FIG. 18, yet another embodiment is seen. In this version,controller 220 is used to operate two separate vacuum lines V_(E), V_(M)from the vacuum source 216. V_(E) is the source line for the milkexpression cycle. V_(M) is a line for conveying and maintaining aminimum baseline vacuum within the breastshield. Note that source 216can also be different vacuum sources, which can be independent of eachother and separately controlled.

It can thus be seen that a variety of different yet precisely determinedactual pressures, as well as rates of change, can now be provided withina breastshield, all pressures being less than ambient for the majorityof the pumping session, if desired. Examples of the kind of methods(curves) for operating a breastshield through a sequence havingdiffering pressure less than ambient are further shown in FIGS. 9, 10and 12.

As indicated in the graphs of FIGS. 9, 10 and 12, negative pressure isalong the y-axis (in millimeters of mercury) and time (in seconds) alongthe x-axis. The pressure is charted with respect to that expected to berealized in the breastshield of a breastpump assembly. In reference tothe particular cycle or sequence of FIG. 9, the amount of pressure isless than 0 mmHg negative, more particularly, between a minimum andmaximum pressure value, for example, −50 mmHg to −150 mmHg. Theregulator maintains a vacuum within the breastshield between a minimumand maximum value along a relatively smoothly rising and fallingsequence. While a “minimum” pressure of −50 mmHg has been generallydiscussed, present thinking of the Inventors yields a desired rangebetween about 15 mmHg and about 60 mmHg negative pressure. For instance,it may be desired in one application of the invention to maintain theminimum vacuum at a level which will enable the breastshield (andrelated structure it is carrying) to be held in place through suction,in a “hands-free” mode of use. It will be noted that whether totally“hands-free” suspension of the breastshield is accomplished, the use ofthe minimum vacuum serves to keep the breastshield positioned about thenipple. Having the nipple become uncentered in a breastshield isundesirable, and the invention is very advantageous in that respect.

FIG. 15, for instance, shows an embodiment for a breastshield having aconstruction on the interior of the funnel surface considered conducivefor “hands-free” use. Funnel 350 is of the type previously discussedwith regard to shields 112, 212. On its interior surface, however, are aplurality of suction channels 354 formed concentrically about the axisof the funnel 350/nipple tunnel 352. The suction channels areperiodically broken (as at areas 356). The suction channels 354 are openinwardly (i.e., facing the breast).

A series of vacuum channels 358 interconnect with the suction channels354. These vacuum channels extend down into the nipple tunnel 352 to apoint where they will extend past any breast and nipple tissue, so as tobe open to the vacuum being generated in the breastshield at thisdownstream end. As can therefore be understood, the vacuum, such as aminimum vacuum, maintained in the breastshield will be conveyed by thevacuum channels 358 to the suction channels 354. A fairly broad area forsuction between the funnel 350 and the breast therein is therebyestablished, which will serve to position, and if sufficient actuallysupport in place, the breastshield. Of course many other designs can bereadily conceived to convey and provide the foregoing “hands-free” typesuction.

In another operation method, as shown in FIG. 10, the amount of negativepressure is given more complexity in the curve over time. Moreparticularly, the regulator can be manipulated to control the pressureto a medium vacuum held for a period of time, between a minimum vacuumand maximum vacuum, for example, a medium vacuum of −175 mmHg (point708) between −150 mmHg to −250 mmHg. FIG. 12 illustrates yet anotherpossible variation when a maximum and minimum vacuum series of cycles isinterspersed with a return to ambient. Plainly, the invention allows awide variety of precisely controlled and tailored pumping sequences tobe effected.

Referring to FIG. 20, another embodiment of a pressure regulator used tomaintain a minimum vacuum is shown. In this embodiment, the valving usedis removed from the breastpump assembly itself, and place much nearer tothe vacuum pump. The type of pump being used is a diaphragm pump, suchas that used in the SYMPHONY breastpump sold by Medela, Inc. Thisembodiment also addresses, in part, two issues: air, from leakage intothe breastshield through gaps between the interface of the breastshieldand the breast, for instance, needs to be expelled from the system; sotoo, air that enters the region between the flexible membrane and thecap within which it reciprocates also needs to be expelled.

Referring once again to FIG. 20 now, the diaphragm pump is generallyindicated at 801. It creates a vacuum by use of a membrane or barrier803 which is reciprocated (in known fashion, but the mechanism of whichis not shown) relative to a pump cap 805. As the membrane 803 pulls awayfrom the cap 805, the expanded volume between the cap interior and themembrane generates a negative pressure, which is initially transmittedthrough the port 804 in the cap 805 and into conduit 811; here, thisconduit structure is integral with the cap 805, although it need not beso. Cap 805 would itself snap-fit or interference fit on a basestructure (also not shown) to which the membrane 803 is attached orfitted.

Downstream from the conduit 811 is a valving structure used to establishand maintain the minimum vacuum. Conduit or passage 811 opens into achamber 812 formed by valving housing 814. The valving mechanism is anumbrella valve 817 that is combined with a duck bill valve 813; thesecould alternatively be separated along a common channel. Valvingmechanism 813/817 seals against a surface bulkhead (or shoulder) 821,which has a passage 819 extending between upstream and downstream sidesof umbrella valve 817. The umbrella valve 817 seals along its undersideagainst surface 815. The duckbill valve 813 extends into the chamber812.

The bulkhead 821 is itself part of a mounting assembly 818 which isdesigned to slide and fit within the housing 814, for easy insertion andremoval of the valving mechanism. To this end, a packaging seal 823 (oring) sits proud in a circumferential channel 820 of the bulkhead, toseal the two pieces when fit together.

The foregoing housing and mounting assembly connects to the breastshield assembly (not shown but downstream) by a hose 829. The hose 829press fits onto a tube fitting barb 827 that is part of a plug havingflanges yielding seal ridges 825. A channel 830 extends through the barband plug.

Finishing this valving arrangement is a one way (anti-pressure) reedvalve 807, which is mounted via a biasing hinge 806 to the cap in amanner to open and close (seal against) hole 809 that extends throughthe cap 805 into the space between the cap interior and membrane.

In operation, when vacuum is generated (pulled) by the diaphragm pump801, umbrella valve seals and duckbill valve 813 opens. Valve 817 closesat the minimum vacuum however, upon release of the vacuum stroke. Anyexcess air on the return stroke of the diaphragm is expelled through airvent created at hole 809.

FIG. 21 shows a collection bottle and catch chamber valve assembly foruse with the valving arranging described with respect to FIG. 20. Breastshield assembly catch chamber 621 connects the breast to the pumpassembly in the usual fashion, as does the bottle 628 to the breastpumpassembly collar (via screw threading 834 here). The collection bottle628 is also shown using a sealing gasket 833, although this may bedispensed with given an adequate interference seal. Typical of some ofthe foregoing described assemblies, a valve 174 releasably seals againstthe surface of 172 to open and close the catch chamber. To control thepressure or vacuum in the collection bottle, an orifice passage 835allows a small flow of air from the collection bottle into the breastpump conduit system. As the breast shield cycles to higher vacuumincreasing the airflow through passage 835, this increases the vacuum inthe collection bottle. The vacuum in the collection chamber 621 will begreater than the minimum control vacuum set by umbrella valve 817. Theone way valve 174 will open to prevent vacuum in the breast shield frombeing less than the collection bottle. Expelled milk will be pushedthrough the valve 174, and the vacuum levels between the chamber 621 andthe bottle will both finish the cycle and equalize, reaching the controlvacuum set by umbrella valve 817.

FIG. 22 has all the features of FIG. 21, but further includes anothervalve 838. This is a one way reed valve 838 similar to that of 807 (butmounted using an integral pin or plug 839). The flap of the reed valvecovers a hole or passage 840. Only when the control vacuum is set at orabove atmospheric pressure will the one way valve 838 open to expel air.

It will be noted that in most of the foregoing embodiments (such asshown in FIGS. 1-5, 13, 14, 16-17, 20-22, and 23-27), the regulatorymechanism is separate from the vacuum pump. That is, it is external tothe vacuum pump housing; or put another way, it is downstream from anoutput of the vacuum pump. This would be in an airline from the vacuumpump to the breastshield, for one example (such as shown in theembodiments of FIGS. 6 and 20), or on the breastshield assembly itself.These arrangements that are separate from the vacuum pump are to becontrasted with the embodiment of FIG. 18, where the regulation for aminimum vacuum is contained in the vacuum pump mechanism itself, and notexterior to (outside of) the vacuum pump.

Thus, while the invention has been described herein with relation tocertain embodiments and applications, those with skill in this art willrecognize changes, modifications, alterations and the like which stillcome within the spirit of the inventive concept, and such are intendedto be included within the scope of the invention as expressed in thefollowing claims.

1. An improved breastpump for the expression of mother's milk, thebreastpump including a breastshield assembly and a vacuum pump locatedin a housing separated from the breastshield assembly and communicatingwith the breastshield assembly, comprising: a valving mechanismassociated with a breastshield chamber in tubing to the breastshieldassembly or in the breastshield assembly, and separate from the vacuumpump housing to maintain at least a minimum negative pressure within thebreastshield chamber throughout at least some repeated cycles in abreastpumping session.
 2. The improved breastpump of claim 1 whereinsaid breastpump is further adapted to manual operation.
 3. The improvedbreastpump of claim 1 wherein said valving mechanism is further adaptedto be operated in conjunction with a motor driven vacuum pump.
 4. Theimproved breastpump of claim 1 wherein said minimum pressure is within arange of about −15 mmHg to −60 mmHg.
 5. The improved breastpump of claim1 wherein said mechanism is physically located on said breastshield aswell as separate from the vacuum pump.
 6. The improved breastpump ofclaim 1 wherein said mechanism is located remote from said breastshieldas well as separate from the vacuum pump.
 7. The improved breastpump ofclaim 1 wherein said minimum negative pressure establishes an amount ofsuction between the breast and said breastshield assembly capable ofsupporting said breastshield assembly in place on the breast.
 8. Theimproved breastpump of claim 7 wherein said breastshield chamber has aplurality of suction channels along an interior surface of abreastshield funnel so as to provide an increased area of suctionbetween said interior and the breast.
 9. The improved breastpump ofclaim 8 further comprising a series of vacuum channels along saidinterior surface of the breastshield funnel, said vacuum channelsinterconnecting with said suction channels.
 10. The improved breastpumpof claim 9 wherein said suction channels are formed concentrically abouta longitudinal axis of said breastshield funnel.
 11. The improvedbreastpump of claim 10 wherein said suction channels are periodicallybroken along said interior surface of said breastshield funnel.
 12. Theimproved breastpump of claim 7 wherein said minimum negative pressure issufficient to support said breastshield assembly in place during milkexpression without any other means of support required.
 13. The improvedbreastpump of claim 1 wherein said valving mechanism is a simple one-wayvalve located in an airline in communication with said breastshieldchamber, said valve having a biased opening operable to seal itself andthereby close said airline at a desired minimum negative pressure tothereby maintain said minimum negative pressure within saidbreastshield.
 14. The improved breastpump of claim 13 further includingan adjustable pressure regulator in said airline.
 15. The improvedbreastpump of claim 14 wherein said pressure regulator is manuallyadjustable by a user.
 16. The improved breastpump of claim 1 whereinsaid breastpump includes first and second airlines, the first airlinecommunicating negative pressure for milk expression and the secondairline in communication with said breastshield assembly which maintainssaid minimum negative pressure.
 17. The improved breastpump of claim 1wherein said valving mechanism comprises a flexible membrane mounted ona base extending across said airline, said base having at least onepassage therethrough, said membrane having an aperture formedtherethrough adapted to close and seal said base at said desired minimumnegative pressure.
 18. The improved breastpump of claim 1 wherein saidvalving mechanism comprises a flexible membrane, said membrane having apin having disks at each end thereof and a dome defining a hole at anapex end of said dome through which the pin passes, said dome beingformed on said flexible membrane, said dome biasing said pin in a mannerto place one of said disks in sealing engagement with said dome baseopening at a preset negative pressure within said vessel.
 19. Theimproved breastpump of claim 18 wherein the dome further comprises aseal ring at the opposite end against which said one of said disks ofthe pin seats.
 20. The improved breastpump of claim 19 wherein the domeis further provided with an opening to allow air to pass from one sideof the dome to the other until said preset negative pressure isachieved.
 21. The improved breastpump of claim 1 further comprising apressure regulator having a duckbill valve which is one way toward thebreastshield chamber and closable in communication with said vesselinterior at a preset negative pressure within said vessel interior. 22.The improved breastpump of claim 21 wherein said second duckbill valvehas a flow which is one way toward said vacuum pump.
 23. An improvedbreastpump for the expression of mother's milk comprising a breastshieldassembly, a vacuum pump located in a housing separated from thebreastshield assembly, and a pneumatically operated one-way valvelocated in tubing to the breastshield assembly or in the breastshieldassembly downstream from said vacuum pump housing communicating with abreastshield chamber to maintain at least a minimum negative pressurewithin said breastshield assembly throughout repeated cycles in abreastpumping session.
 24. The improved breastpump of claim 23 whereinsaid breastpump is further adapted to manual operation.
 25. The improvedbreastpump of claim 23 wherein said minimum negative pressure is apressure within a range of about −15 mmHg to about −60 mmHg.
 26. Theimproved breastpump of claim 23 wherein said breastshield assembly has abreast-receiving funnel portion including a nipple tunnel, the one-wayvalve being located within said nipple tunnel for controlling the flowof expressed milk from said breastshield assembly through a channel to acollection chamber.
 27. The improved breastpump of claim 26 wherein saidone-way valve comprises a base and a flexible membrane operativelyengaged to said base.
 28. The improved breastpump of claim 27 whereinsaid base is provided with at least one opening to allow flow ofexpressed milk therethrough.
 29. The improved breastpump of claim 28further comprising a pressure regulator.
 30. The improved breastpump ofclaim 29 wherein said pressure regulator includes a manual adjustmentdevice located in a pressure channel structure, said pressure channelstructure communicating across opposite sides of said base.
 31. Theimproved breastpump of claim 30 wherein said flexible membrane islocated downstream on said base, said flexible membrane closing saidbase opening and sealing said base when a vacuum is present in saidbreastshield assembly upstream from said base which is relativelygreater, or more negative, than the pressure downstream from said base.32. The improved breastpump of claim 29 wherein said flexible membranehas an aperture formed therethrough for air passage and adapted to closeand seal said base at a predetermined negative pressure within saidbreastshield assembly.
 33. The improved breastpump of claim 32 whereinsaid aperture comprises two slits.
 34. The improved breastpump of claim29 wherein said pressure regulator includes a pin having disks at eachend thereof and a dome defining a hole at an apex end of said domethrough which said pin passes, said dome being formed on said flexiblemembrane, said dome biasing said pin in a manner to place one of saiddisks in sealing engagement with a dome base opening at a presetnegative pressure within said breastshield assembly.
 35. The improvedbreastpump of claim 34 wherein said dome further comprises a seal ringat said dome base opening against which said one of said disks of saidpin seats.
 36. The improved breastpump of claim 35 wherein said dome isfurther provided with an opening to allow air to pass from one side ofsaid dome to the other until said preset negative pressure is achieved.37. The improved breastpump of claim 29 wherein said pressure regulatorcomprises a duckbill valve which yields a one way flow toward saidbreastshield chamber and is closable in communication with saidbreastshield chamber at a predetermined negative pressure within saidbreastshield chamber.
 38. The improved breastpump of claim 37, furtherincluding a second duckbill valve, said second duckbill valve being incommunication with said breastshield chamber for milk and air flow, andyielding a one way flow toward said vacuum source.
 39. The improvedbreastpump of claim 23 wherein said breastshield chamber has a pluralityof suction channels along an interior surface of a breastshield funnelso as to provide an increased area of suction between said interior andthe breast to support said breastshield in place on the breast.
 40. Theimproved breastpump of claim 39 further comprising a series of vacuumchannels along said interior surface of the breastshield funnel, saidvacuum channels interconnecting with said suction channels.
 41. Theimproved breastpump of claim 40 wherein said suction channels are formedconcentrically about a longitudinal axis of said breastshield funnel.42. The improved breastpump of claim 41 wherein said suction channelsare periodically broken along said interior surface of said breastshieldfunnel.
 43. The improved breastpump of claim 23 wherein said minimumnegative pressure is sufficient to support said breastshield assembly inplace during milk expression without any other means of supportrequired.
 44. A method for breastpumping comprising: providing abreastshield assembly having a portion within which a woman's breast iscapable of being received and within which a negative pressure can begenerated to pull upon the breast; supplying a source of negativepressure located within a housing in communication with saidbreastshield portion; operating said source of negative pressure torepeatedly pull upon the breast; and maintaining a minimum negativepressure within said breastshield portion throughout at least part ofsaid operation of said source of negative pressure using a mechanismlocated in tubing to the breastshield assembly or in the breastshieldassembly and separate from the housing of the source of negativepressure.
 45. The method of claim 44 wherein said operating stepcomprises repeated cycles of increasing then decreasing vacuum, and saidminimum negative pressure is maintained during at least some consecutivecycles.
 46. The method of claim 45 wherein said minimum negativepressure level is varied between some cycles.
 47. An improved breastpumpfor the expression of mother's milk comprising a breastshield assemblyincluding a pressure-sensitive valve device associated with thebreastshield assembly and located in tubing to the breastshield assemblyor in the breastshield assembly and downstream to a housing containing asource of negative pressure that is remote from said breastshieldassembly and connected thereto with a vacuum line, said valve device hascooperating elements which close at a minimum negative pressure that ismaintained in repeated cycles in a breastpumping session.
 48. Theimproved breastpump of claim 47 wherein the breastshield assembly has aninterior portion within which a woman's breast is configured to bereceived and a first valve at an opposite end of said portion forcontrolling the flow of expressed milk from the breastshield assembly toa collection container and closing said interior portion.
 49. Theimproved breastpump of claim 48 wherein the breastshield assembly isprovided with a conduit structure which extends across said first valve,said conduit structure communicating between said breastshield interiorportion and downstream of said first valve.
 50. The improved breastpumpof claim 49 wherein a pressure regulator is located within said conduitstructure.
 51. The improved breastpump of claim 50 further comprising asecond valve which is said pressure regulator, said first and secondvalves each being one way valves.
 52. The improved breastpump of claim51 wherein each valve is of a duckbill type.
 53. An improved method foroperating a breastpump for the expression of mother's milk comprisingoperating a breastpump assembly to maintain a minimum vacuum levelwithin a breastshield throughout at least some repeated cycles in abreastpumping session and also regulating pressure within a collectioncontainer to operate a valve controlling milk flow from a collectionchamber downstream from said breastshield to said collection container,wherein said valve opens to release milk into said collection containerby reduction in vacuum in said collection container to a level of vacuumabout the same as or below that of said collection chamber, and tomaintain the minimum vacuum level in the breastshield.
 54. The improvedmethod of claim 53, wherein the vacuum in said collection containeroperates to open said valve to milk flow when vacuum within saidcollection container exceeds said minimum vacuum maintained within saidbreastshield.
 55. The improved method of claim 53, wherein said minimumvacuum level for said breastshield gradually increases in a manner tomatch an increasing vacuum in said collection container, until a desiredupper bound to a vacuum level range is achieved.
 56. An improvedbreastpump for the expression of mother's milk, comprising: abreastshield having an interior within which a woman's breast includingthe nipple is configured to be received, a mechanism communicating withsaid breastshield interior that maintains at least a minimum negativepressure within the breastshield throughout at least some consecutivecycles in a breastpumping session; a milk container communicating withsaid breastshield interior through a milk catch chamber intermediatesaid milk container and said breastshield, to receive milk therefrom; asource of vacuum communicating with said breastshield interior and saidmilk container, said source of vacuum being operated to generatenegative pressure in said breastshield; and a valve structure betweensaid milk container and said catch chamber, said valve structureincluding a first pneumatically operated valve capable of opening andclosing for milk passage through use of a vacuum level in said milkcontainer that is about the same as or less than that of said catchchamber and to maintain the minimum vacuum level in the breastshield.57. The breastpump of claim 56 wherein said mechanism comprises a baseand a flexible membrane operatively engaged to said base, said base isprovided with at least one opening to allow flow of expressed milktherethrough, said flexible membrane is located downstream on said base,said flexible membrane closing said base opening and sealing said basewhen a vacuum is present in said breastshield upstream from said basewhich is relatively greater, or more negative, than the pressuredownstream from said base, said flexible membrane having an apertureformed therethrough for air passage and adapted to close and seal saidbase at a predetermined negative pressure within said breastshield. 58.The improved breastpump of claim 57 wherein said aperture comprises twoslits.
 59. An apparatus for generating a minimum negative pressure overan area of the human body comprising: a pressure chamber having aninterior and a perimeter sized to surround and be sealingly engaged withthe area, an airline extending from the vessel interior to a source ofnegative pressure, and a valve mechanism communicating with the airline,the source of negative pressure being operated to generate repeatedcycles of increasing and decreasing pressure, the valve mechanismcomprising three cooperating one-way valves and being located adjacentsaid pressure chamber, said valve mechanism is adapted to close at adesired minimum negative pressure thereby closing the airline andmaintaining a desired minimum negative pressure.
 60. The apparatus ofclaim 59 wherein the three valves comprise an umbrella valve, andduckbill valve, and a reed valve.
 61. The apparatus of claim 60 whereinthe duckbill valve is located in between the umbrella valve and the reedvalve.
 62. The apparatus of claim 59 wherein said source of negativepressure is an expansible chamber device using an element that is movedrelative to a chamber wall to generate a pressure change, one of saidvalves comprising an outlet to said chamber through which air in thechamber is expelled, the other two valves being a duckbill and umbrellavalve combination, said duckbill valve allowing air flow in thedirection of the expansible chamber device, said umbrella valve allowingair flow in the direction of the pressure chamber.
 63. The apparatus ofclaim 59 wherein said pressure chamber is a breastshield of abreastpump.
 64. The apparatus of claim 59 wherein said pressure chamberis a wound therapy device.
 65. A breastpump for the expression ofmother's milk comprising: a breastshield assembly; a vacuum pump locatedwithin a housing and providing a vacuum to the breastshield assembly;and a valving mechanism associated with a breastshield chamber in tubingto the breastshield assembly or in the breastshield assembly andseparate from the vacuum pump housing to maintain at least a minimumnegative pressure within the breastshield chamber throughout at leastsome repeated cycles in a breastpumping session, said valving mechanismhaving elements that are biased to close at a desired minimum negativepressure within the breastshield chamber.